Class ProjectProblems

Support for managing project problems. Project freshly checkout from
VCS can has broken references of several types: reference to other project,
reference to a foreign file, reference to an external source root, reference
to a library, etc. This class has helper methods for detection of these problems
and for fixing them.

showAlert

Show alert message box informing user that a project has broken
references. This method can be safely called from any thread, e.g. during
the project opening, and it will take care about showing message box only
once for several subsequent calls during a timeout.
The alert box has also "show this warning again" check box and provides resolve
broken references option